1. Field of the Invention
The present invention relates to a rotary-piston internal combustion engine t at includes a casing provided with two side parts or end plates and a piston housing or middle part having a trochoidal surface; an eccentric shaft passes axially through said casing and includes an eccentric on the shaft about which a multi-cornered or triangular piston moves or orbits on roller or needle bearings Sealing parts in piston corners continuously engage the trochoidal surface.
A synchronizing gear or synchromesh is provided between a housing side wall and the eccentric and the eccentric bearing, the sealing parts of the piston and the synchromesh are supplied with lubricating oil via bores in the eccentric shaft and in the eccentric.
In such engines, the eccentric bearings and the gears of the synchromesh are lubricated by cooling oil or by the intake air, essentially without quantitative metering or dosing, which above all requires that the working chambers be sealed against oil passing from the bearing and the gear space, and also results in a high oil consumption Description of the Prior Art
With such known engines, the oil required for cooling of the piston and of the eccentric bearing is conveyed via axial and radial bores in the eccentric shaft and the eccentric in the piston and the eccentric shaft. This eccentric bearing conventionally is a slide bearing, through which, in order to keep the bearing "floating", respectively according to size several liters of oil per minute must be pressed under pressure. This oil discharges from the bearing into the piston for the cooling of which likewise these and larger oil quantities are required or needed per time unit. Also, if a rolling bearing were employed in place of the sliding bearing, the roller bearing is located in the oil flow cooling the piston. Via an arrangement of valves controlled by centrifugal force and located in bores of the eccentric shaft, the supply of cooling oil in the piston inner chambers or spaces is to be controlled or regulated corresponding to the speed of the eccentric shaft. Also such a valve arranged in an eccentric was proposed that upon closing of the oil supply to the eccentric bearing increases at higher rotational speeds and reference can be made to U.S. Pat. No. 4,293,289-Morita dated Oct. 6, 1981 particularly in FIG. 3 thereof.
The cooling of the piston with these oil quantities or oil volume necessary for doing so, as in general on the whole every oil excess in the bearing and drive or transmission chamber of the engine, makes necessary oil-interior seals with respect to the working chambers or spaces, since the oil passing over thereto delivers or provides a considerable and important contribution to worsening of the combustion exhaust or waste gases.
U.S. Pat. No. 3,213,801-Venygr dated Oct. 26, 1965 can be noted because the cooling oil for the piston only enters via the sliding bearing into the piston inner space or chamber and discharges again, which piston inner chamber is completely closed-off as to the bearing space or chamber and gear chamber and the piston outer side. To that extent with this arrangement also an oil inner seal would be avoided. This machine however belongs to a completely different class or genus, namely that of cellular engines (wing or vane-cell engines), whereby here the vanes are replaced by rollers. These engines differ from the Wankel engines most of all thereby that they are not sealed-off with sealing elements and consequently require oil for parts forming a sealing of the working chambers. Consequently this Venygr patent cannot be taken into consideration for evaluation of the features of the present invention.
The machine or engine of the Venygr disclosure concerns an engine with rolling piston rotors belonging to a completely different genus of machines with a circular-shaped mantle or a housing raceway and a piston not controlled or regulated by a synchromesh drive or transmission. The eccentric of the piston runs upon a friction or sliding bearing through the radial bores of which cooling oil is supplied and discharged in the interior of the piston via bores respectively out of axial bores in the shaft and bores in the eccentric. The oil that passes therethrough serves for cooling of the engine with the rolling piston rotors per se. Thus this machine or engine of Venygr represents nothing different or other than the previously noted friction or sliding bearing machines. Also the machine or engine in order to maintain the necessary oil film for the friction or sealing bearing requires a higher oil pressure and also requires greater through-passage quantities or volume of oil because of the cooling of the piston, as shown by the supply and discharge lines for oil in the shaft and in the eccentric.
U.S. Pat. No. 3,323,713-Wenderoth et al dated June 6, 1967 describes a typical slide-bearing arrangement with oil-cooled piston means. Consequently costly and complex oil inner seals are required including the seals 44, 64 and 76, 78 thereof At most this Wenderoth et al reference includes supply of oil via bores in the shaft and eccentric. This engine of the Wenderoth et al patent has exactly the disadvantages which are to be avoided in accordance with the teaching of the present invention.
U.S. Pat. No. 3,712,766-Jones dated Jan. 23, 1973 can be noted only because here a roller bearing is employed for the piston, which however lies completely in the flow of the pressurized oil, which discharges at an orifice of a passage 28 and flushes or flows through the piston under pressure and in large quantities or volume.
The Jones disclosure has a piston that is fully oil cooled for which the aforementioned through-passage quantities or volume are necessary or required in the same manner as with the Morita et al disclosure. The oil pressure is sprayed out of a bore into a right hollow space or chamber of the eccentric and from there is pressed by centrifugal force effect via another bore into the roller bearing and from there comes or reaches into the piston interior spaces or chambers and synchromesh drive or transmission spaces or chambers. The greatest part of the supplied oil is conveyed away or discharged over this path or in this manner. Consequently, the same conditions exist as with
friction or sliding bearing versions.
U.S. Pat. No. 3,832,980-Fujikawa et al dated Sept. 3, 1974 basically has the same applicable comments as for the Wenderoth et al disclosure. The cooling oil for the piston passes nearly completely through the slide bearing thereof, partially through the left shaft bearing, into the piston inner space and gear chamber. Also here the large volume or through-passage of pressurized oil is required and needed and the same is true as stated for the Wenderoth et al disclosure. The inner seal moreover is not drawn or illustrated hereby but naturally is needed and required. The assignee (Kawasaki) of the Fujikawa et al disclosure concerned itself only briefly with such engines.
The two U.S. Pat. Nos. 4,,218,200-Morita et al dated Aug. 19, 1980 and U.S. Pat. No. 4,293,289-Morita dated Oct. 6, 1981 show and disclose a cooling of a piston with a slide bearing and flow or through-passage of large pressurized oil quantities or volume; these two disclosures moreover are limited or restricted to the region of the oil inner seal. A costly and complex double Mazda-oil inner seal is required in order to keep away from the combustion chambers the oil flowing through the engine inner space or chamber. Noteworthy here however is the centrifugal-force-controlled valve and a bore of the shaft, via which at higher rotational speeds additional cooling oil is brought to the outer side of the piston. Consequently large quantities or volumes of pressurized oil exist within the oil inner seal, in any event at higher rotational speeds.
The Morita et al disclosure represents a special situation with which the oil is conveyed from the bearing first into annular spaces or chambers after or behind the oil seals in order to cool the same preferably with the sought or desired higher temperature loads and preferably because of the elastomeric O-ring means located in these seals. Moreover this machine or engine provides a fully oil-cooled piston as proven by the presence or provision of oil seals at a full pressurized oil through-passage via the eccentric bearing in the oil quantities or volumes as set forth.
In FIG. 3 of U.S. Pat. No. 4,293,289-Morita dated Oct. 6, 1981 there is shown a further centrifugal force and spring-control valve 40 which however is to multiply the oil conveying into the slide bearing at higher rotational speeds in that the draining or discharge of the oil via the opening 41 is blocked. The entire oil flowing in the bore 23 consequently at higher rotational speeds comes into the slide bearing.
The prior art disclosures with the exception of U.S. Pat. No. 3,712,766-Jones aIl describe motors or engines with full oil cooling of the piston and with slide bearings between the eccentric and piston. These slide bearings require an oil film produced by a considerable oil pressure upon which oil film the bearings run or operate as well as requiring an oil through-passage of several liters of oil per hour. Since the oil simultaneously is utilized for piston cooling, the oil requirement of the bearing can occur via a supply of cooling oil through the friction or sliding bearing.
It is thus a general state of the art whereby mostly the oil supply occurs via axial and radial shaft bores as shown by the prior art disclosures.
With all of these prior art disclosures there is noted that the engines are described with which the piston bearing lies in the flow of the piston-cooling oil, which is conveyed under pressure in multiple liters per minute while with the present invention per hour only 50 grams of oil or lubricant pass through the roller bearing of the piston. For comparison purposes, reference can be made to the following table of features listing the various prior art disclosures as well as the teaching of the present invention and in which the "X" represents the presence of a feature and the designation "O" represents the lack of a feature.
__________________________________________________________________________ Wende- Venygr roth Jones Fujiwaka Morita Morita Appli- A B C D E F cation __________________________________________________________________________ 1 oil-cooled piston X X X X X X O 2 slide bearing X X O X X X O 3 roller bearing O O X O O O X 4 bore in the shaft X X O O X X X 5 oil discharge from X O O O O O X the shaft only into the bearing 6 oil discharge from O X O* X X X O from the shaft also besides the bearing 7 centrifugal-force- O O O O X X O control valve for oil discharge beside the bearing 8 centrifugal-force- O O O O O X O control valve in eccentric for con- trol or regulation of oil discharge into the bearing 9 centrifugal-force- O O O O O O X control valve in the eccentric for blocking of oil discharge into the bearing during standstill of the machine 10 lip seal ring O O O O O O X around shaft __________________________________________________________________________ *The oil is sprayed or injected from a side part into the piston inner chamber and comes through a bore in the eccentric into the middle of the roller bearing.